Prosthetic locking hinge



Nov. 12, 1957 N. J. BROWN EIAL 2,812,961

PROSTHETIC LOCKING HINGE Filed June 21, 1955 3 Sheets-Sheet 1 2| INVENTORS j NOEL J. BROWN RALPH K. DAUGHERTY 31 7 4% v ATTORNEY Nov. 12, 1957 N. J. BROWN ETAL 12 RROSTHETIC LOCKING HINGE Filed June 21, 1955 3 Sheets-Sheet 2 INVENTORS NOEL J BROWN RALPH K. DAUGHERTY B) .L W a 1A...

ATTORNEY Nov. 12, 1957 N. J. BROWN ETAL ,8 ,96

PROSTHETIC LOCKING HINGE Filed June 21, 1955 3 Sheets-Shet 3 mmvrozs NOEL J BROWN RALPH K DAUGHERTY rates emit PROSTHETIC LGCKING HINGE Application June 21, 1955, Serial No. 516,832

7 Claims. ((11. 28714) The present invention relates to prosthetic hinge structures such as locking hinges for elbows, and is concerned more particularly with an improved elbow locking hinge construction which is simple and rugged in its construction, and which is particularly adaptable to an elbow disarticulation arm.

In certain types of prosthetic joints, particularly in an elbow disarticulation arm, the hinge requirements of the arm are such that an outside locking hinge must be provided to get a proper hinge location for movement of the artificial forearm section. Consequently, the design of such a locking hinge presents severe problems in space, strength and location of the parts, and in getting the proper operation in the limited space available. Also in such types of locking hinges, as well as other types, it is common practice when the elbow hinge is unlocked for adjustment of the forearm section with respect to the humeral section to employ one movement to release the locking element from its latched, unlocking condition, and another movement is used to move the locking element into active locking position so that the hinge becomes rigid. In this connection it is highly desirable that the same shoulder movement that controls the hinge lock to release the locking element for movement to a locking position should also control and provide for its carrying to its home locking position in engagement with the element to be locked. In this way, there is no opportunity for the forearm section to get displaced from the adjusted position because of the requirement for two shoulder movements to exercise control.

The prosthetic locking hinge of the instant invention attains the foregoing objects, among others, as described in the following specification, taken in connection with the attached drawings, in which:

Figure 1 is a perspective view of a prosthetic elbow disarticulation arm employing an outside locking hinge embodying the present invention.

Figure 2 is an enlarged exploded view of the outside locking hinge.

Figure 3 is an enlarged elevational view of the hinge, with certain outside casing components removed, showing one condition of the parts in which the hinge is locked, and the control cable is untensed.

Figure 4 is a view similar to Figure 3 in which the hinge is unlocked, and the control cable is tensed.

Figure 5 is a view similar to Figures 3 and 4 illustrating another operating condition of the parts in which the control parts are latched in unlocked position, and the control cable is untensed.

Figure 6 is a similar view to Figure 5 showing the parts with the control cable tensed, and the unlocking operation for the locking slide commenced, the parts being shown just prior to actual unlocking and release of the locking slide.

Figure 7 is a view similar to Figure 6 showing a subsequent condition of the parts with the locking slide in locking position, and the cable still tensed.

" atent O Referring to Figure 1, there is shown a prosthetic elbow disarticulation arm including a forearm section 10 which is hinged to the humeral section 11 by an outside locking hinge 12 and a conventional hinge connection 13 in alignment with the hinge axis of the hinge 12.

Referring to Figures 1, 2 and 3, the locking hinge 12 comprises an outer casing and housing member 14, in which preferably all of the operating parts of the mechanism are contained, and a composite outer cover element comprising straps 15 and 16, which together form the inside cover for the lock. The forearm connecting member is in the form of a gear sector 17 having a strap extension 18 for imbedding in the plastic form. The member 16 has a similar strap extension 19 for imbedding in the plastic of the humeral section. Strap 15 has an extension which can be bent around the end of the elbow and fastened to a similar extension from the other hinge connection 13, and then imbedded in the plastic. It can be also cut off if not desired.

A pivotal connection between the two sections of the hinge lock is provided by a securing screw 21 (Figures 1 and 2) which extends through a central opening 22 of the housing 14, a bushing member 23 which seats in a central aperture 24 of the gear sector 17, the screw 21 being threaded into the outer cover 15 and 16 which contains a threaded central opening 26. The limited pivoting movement between the forearm section 10 and the humeral section 11 is provided by an arcuate slot 27 in the cover member 16, and a pin 28 secured by a press fit in the gear sector 17 engaging in the slot 27.

The housing 14 (Figures 2 and 3) includes a fiat portion 31 on which the gear sector 17 seats, which is partially encompassed by a raised angular flange segment or guard 32 leading to one of two opposite spaced side rails or guides 33 and 34 for a locking slide 36. The slide 36 includes a tooth 37 to cooperate with the tooth spaces of the gear sector 17, a head 38 having parallel flat sides which are closely fitted to and slidably engage the guides 33 and 34 of the housing 14 and also having an extension 57 projecting from one side of the head 38 and having reduced width and thickness with respect to the head 38 to provide for proper spacing of other parts in the hinge, as will be apparent later. At the left of the guideway formed by the guides 33 and 34 and adjacent the rail 33, there is a recessed surface 39 providing, with a recessed surface 41 of the rail 33, a mounting for various operating parts including a keeper pawl 42 pivoted on a pin 43 secured in a suitable aperture in the guide 33, the keeper pawl 42 being urged clockwise by a leaf spring 44 extending across the surface 39 and seated in a suitable slot 46 of the housing.

The locking slide 36 (Figures 2 and 3) has associated therewith a driver pawl which is mounted on the locking slide 36 and functions both to receive the drive for restoring the locking slide to inactive position, and to provide a latch pawl for holding it in such inactive position. Adjacent the keeper pawl 42 is a driver pawl 46 pivoted on a pin 47 seated in an aperture of the locking slide 36, and spring urged in a clockwise direction by a leaf spring 48, secured in a groove 49 of the locking slide 36' The assembly comprising the locking slide 36 and the driver pawl 46 is spring urged to the right as viewed in the drawings by a compression spring 51, seated in a suitable recess in an end wall 52 of the housing 14 at one end, and in a suitable recess in the locking slide 36 at its other end.

Associated with the other parts described is a control cam slide 56 (Figures 2 and 3), which is slidably mounted between the guide Wall 33 and the extension 57 of the locking slide 36. The slide 56 has a cam nose 58 for engagement alternately with a drive tooth 61 of. the

Patented Nov. 12, 1957 driver pawl 46, or with an inclined surface 62 of the keeper pawl 42, as will later be described in detail. This control cam slide 56 has secured thereto a control cable 63 extending through an aperture 65 into a suitable flexible tube 64 secured in the end wall 52, and this control cable 63 has placed thereabout a compression spring 66 which seats at one end in a recess in the control cam slide 56, and at the other end seats against the shoulder 67 of the housing 14, This spring 66 tends to urge the control slide 56 to the right against a face 68 of the locking slide 36, so that a pull on the control cable 63 is necessary to effect displacement of the control cam slide 56 and is used in controlling operation of the parts, as will be described.

In the position of the parts shown in Figure 3, the cable 63 is untensed, the locking slide 38 has its tooth 37 engaged with gear sector 17, the driver pawl 46 is spring urged so as to engagecam nose 58 of the lock slide 56 as a stop, and the keeper pawl 42 is urged clockwise by its associated spring to place a cam surface 71 thereof in-engagement with a latching tooth 72 of the pawl 46, the resulting condition of the parts, placing drive tooth 61 of the pawl 46 in path of movement of the cam nose 58 to be operated thereby, and the pawl 42 being held in a retracted position, out of the path of movement of cam nose 58. The driver pawl 46, and the keeper pawl 42 have respective latching control teeth 73 and 74 for engagement with each other in the retracted positions of the locking slide 36 shown in Figures 4 and 5.

Figure 4 shows an operating position midway between that shown in Figure 3 and that shown in Figure 5, the cam control slide 56 is being retracted by a shoulder movement or pull on cable 63. The nose 58 of slide 56 is engaged with the tooth 61 of the driver pawl 46, moving the locking slide 36 to disengage its tooth 37 from the gear sector 17, and acts to move the parts rearwardly until the keeper pawl 42 can snap clockwise under the action of its spring 44 to engage the teeth 73 and 74 as shown in Figure 4. The latching control teeth 73 and 74 serve to provide a preliminary latching of the locking slide 37 in retracted position, as shown in Figure 4, where the movement of the parts is still taking place. Upon release of the driver pawl 46 by the cam nose 58 at the instant the tension on the cable 63 is relaxed, the keeper pawl 46 is moved slightly counter-clockwise, as indicated by the arrow in Figure 5, and the end 70 of the keeper pawl 42 moves into locking engagement with the latch tooth 72 of the driver pawl. The parts are maintained in this condition with the cable 63 untensed and the springs 51 and 66 active to maintain the locking slide 36 and the cam slide 56 in the position shown.

In the transition of the parts from position shown in Figure to that shown in Figure 7, including the midway point shown in Figure 6, only one shoulder movement of the wearer of the prosthetic arm is required, the parts having been conditioned so that the driver pawl 46 is out of the path of the cam nose 58, and the cam surface 62 of the keeper pawl 42 is aligned therewith. Consequently, upon subsequent pulling of the cable 63 the rounded edge of the cam nose 58 engages the cam surface 62, as shown in Figure 6, beginning the unlatching movement of the keeper pawl 42. Thus the locking slide 36 can be returned by the spring 51 to move tooth 37 into locking engagement with gear sector 17, even though the cable 63 be maintained in tensed position, as shown in Figure 7. In this condition of the parts the hinge is locked, the cable is still tensed until the shoulder-controlled pull thereof is released to allow return to the position shown in Figure 3, where the driver pawl 46 is again in active position, and the keeper pawl 42 is in inactive position.

' The locking tooth 72 of the driver pawl 46 is adapted for engagement with the keeper pawl 42 to maintain the parts in assembled condition upon partial disassembly 4 so that the gear sector 17 is no longer in position to hold the locking slide 36.

The above functioning of the parts is made possible by virtue of the fact that the leaf spring 44 is stronger than the leaf spring 48, so that with the parts positioned, as shown in Figure 5, for example, the tension or thrust exerted by the leaf spring 44 overcomes the leaf spring 48 to move the parts into position where cam nose 58 is operatively in line with the inclined surface 62 of the keeper pawl 42.

It will be obvious that while the hinge lock shown is particularly adaptable to an elbow disar'ticulation arm because of the compactness and thinness of its structure, it has other uses and, for example, can be used in a polio brace, a leg brace, with short-below-elbow arms, and in special childrens arm appliance applications.

While we have shown and described a preferred form of the invention, it will be apparent that the invention is capable of variation and modification from the form shown so that the scope thereof should be limited only by the scope of the claims appended hereto.

We claim:

1. In a prosthetic locking hinge, respective first and second hinged sections having a pivotal connection with each other providing for relative adjustment therebetween,

a locking slide mounted for movement on one of said sections between a locking position with the other of said sections and a retracted unlocking position with respect thereto, a drive pawl pivotally mounted on said locking slide, and having a drive tooth and a latch tooth on the same side thereof, a keeper pawl pivotally mounted on said one section and having a latch tooth for latching engagement with the latch tooth of the drive pawl in the unlocking position of said slide, a drive and control cam adjacent to said locking slide and mounted to provide a similar path of movement, means for controlling said drive pawl in the locking position of said slide to place its drive tooth in alignment with said cam for operation thereby, means for controlling the position of said pawls in the unlocking position of said slide to place said drive tooth out of the path of movement of said cam and to position said keeper pawl for disabling thereof upon movement of said cam, said keeper pawl being more remote from said cam than said drive tooth and said cam maintaining said drive pawl out of the path of movement of said cam to provide free return of said locking slide to its locking position with said cam operatively engaged with said keeper pawl.v

2. In a prosthetic locking hinge, respective first and second hinged sections having a pivotal connection with each other providing for relative adjustment therebetween, a locking slide mounted for'movement on one of said sections between a locking position with the other of said sections and a retracted unlocking position with respect thereto, a drive pawl normally mounted on said locking slide, a keeper pawl normally mounted on said one section for latching engagement with the drive pawl in the unlocking position of said slide, a drive and control cam adjacent to said locking slide and mounted to provide a similar path of movement, spring means for controlling said drive pawl in the locking position of said slide to place it in alignment with said cam for operation thereby, spring means for controlling the position of said pawls in the unlocking position of said slide to place said drive pawl out of the path of movement of said cam and to position said keeper pawl for disabling thereof upon movement of said cam, said cam maintaining said drive pawl out of the path of movement of said cam to provide free return of said locking slide to its locking position with said cam operatively engaged with said keeper pawl.

3. In prosthetic locking hinge, a first hinge section, a second hinge section, a pivotal connection therebetween providing for adjusting movement of said first hinge section, locking means mounted on the second hinge section for movement between an active position in locking engagement with the first hinge section and an inactive position, a control member for said locking means having a path of movement and mounted on said second hinge section, control means extending from said control member to a point of operation by the user of the prosthetic hinge for effecting movement thereof along said path, drive pawl means on said locking means and mounted for movement into and out of the path of said control member, keeper pawl means mounted on said second hinge section and movable into and out of the path of movement of said control member, said keeper pawl means being effective when in said path of movement to latch said drive pawl means and said locking means in the inactive position of the latter, and means responsive to successive operations of said control means for placing said drive pawl means and said keeper pawl means alternately in the path of movement of said control member.

4. In a prosthetic locking hinge, a first hinged section having a gear sector thereon, a second hinge section having a pivotal connection with said first hinge section, a" locking slide mounted on said second section and having a locking tooth thereon for cooperation with said gear sector, spring means urging said locking member from a retracted position to a locking position, a control cam carried by said second section and having a path of movement therealong, spring means urging said control cam in the same direction as said locking slide from a retracted position to an inactive position, a drive pawl pivotally mounted on said locking slide and having a drive tooth for engagement by said control member and also having a latching tooth, a keeper pawl mounted on said second section and having a latching tooth for engagement with said first-named latching tooth, said keeper pawl with its latching tooth engaged with the latching tooth of said drive pawl presenting a cam surface to said cam whereby retraction of said cam in response to a control movement of the wearer moves said cam into engagement with said cam surface, thereby disengaging said latching teeth, and allowing said drive pawl and said locking slide to move to active locking position, with said cam in retracted position.

5. A prosthetic locking hinge, as recited in claim 4, in which said second hinge section comprises a housing or frame member including opposite parallel guides, said locking slide including a head positioned between and guided by said guides, said locking slide also including an extension of less thickness and width than the head of said locking slide, and said driver pawl being mounted on said portion of reduced thickness, and said cam being mounted between said extension and one of said guides.

6. A prosthetic locking hinge, as recited in claim 4, in which said drive pawl and said keeper pawl include respective pairs of latching teeth, including a pair for effecting a preliminary latching of said drive pawl and said locking slide, and a pair for thereafter effecting a. final latching engagement of said pawls.

7. In a prosthetic locking hinge, a first hinge section, a second hinge section, a pivotal connection therebetween providing for adjusting movement of said first hinge section, locking means on said hinge for locking said sections against relative movement, a control member for said locking means, control means extending from said control member to a point of operation by the user of the prosthetic hinge for effecting movement thereof, latch means for maintaining said locking means in unlocking position, and means responsive to a single unidirectional movement of said control means for releasing said latching means and for freeing said locking means for movement from said unlocking position to its locking position.

References Cited in the file of this patent UNITED STATES PATENTS 423,840 Ulmer et al. Mar. 18, 1890 688,936 Devol Dec. 17, 1901 1,072,593 Erz Sept. 9, 1913 2,570,581 McIntyre Oct. 9, 1951 

